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I. L. MERRELL.

- STEAM BOILER FURNACE. I No. 294,654. v Patented Mar. 4, 1884.

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Patented Mar. 4, 1884.

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ATENT ISAAC L. MERRELL, OF SAN FRANCISCO, CALIFORNIA.

STEAM-BOILER FURNACE.

SPECIFICATION forming part of Letters Patent No. 294,654, dated March 4, 1884.

Application filed August 4, 1883.

{F0 all whom it may concern-.-

Be it known that I, ISAAC L.- MERRELL, a citizen of the United States, residing at San Francisco, in the county of San Francisco and State of California, have invented certain new and useful Improvements in Steam-Boiler Furnaces, of which the following is a specification.

' My invention relates to certain improvements in furnaces adapted for theheating of steam-boilers placed above the flame and combustion chamber; and the object of my in-' vention is to provide a furnace with an interior coil of pipes or tubing, from which jets or sprays of superheated steam are thrown into the fire-box, for the purpose of increas- Similar letters of reference are used to designate like parts throughout the several figures.

The steam-boiler A is provided with the usual steam-drum, B.

G C are the side walls, and D the grate-bars, which are secured in place in the usual man- 1161.

Upon either side of the combustion-chamber, and upon the grate-bars, I lay a narrow cast-iron plate, E, which extends the whole length of the said combustion-chamber, and upon these plates I build a low and narrow wall or bench-wall, F. The bricks which compose these walls may be of the ordinary fire-brick, or may be formed of crucible-clay, or may be of a mixture of clay and asbestus, and laid in a mortar or cement largely composed of asbestus, for the purpose of insuring a longer endurance or resistance to the action of heat. Upon the bench-walls I lay the steam-coil G, the lower section of which alone (No model.)

rests upon the benchavall, while the other sections rise above and are in vertical alignment with the lower section, and are secured to the furnacewalls by suitable hooks or clamps. It should here be remarked that these steam-coils do not extend across the face of the bridge-wall, as that would bring them into too direct contact with the flames passing over the said wall, but only extend along the side and front walls, as shown in plan in Fig. 2; and, also, that the bench-wall is not extended across the face of the front wall, because the natural draft of the furnace will blow the flames away'from the front wall and toward the rear of the furnace; and as the principal object in employing these benchwalls is to protect the steam-coils as much as possible from the direct action of the flames, it will be readily seen that their employment at this point would be unnecessary. The upper steam-coil is extended through the side wall, and is connected by apipe, H, having a suitable shut-off cock, I, with the steam-drum B, while the lower section of the coil is provided with a continuous series of perforations,

J, facing the interior of the fire-box, and

through which the steam, after having been superheated in its passage through the upper .coils or sections, is blown into the combusconstruction it will be seen that I am enabled to provide a means whereby the degree of heat may be greatly increased, and the smoke, gases, vapors, and other products of 'combustion may be consumed before leaving the firebox, through the medium of the jets or spray of superheated steam thrown into the firebox; and, furthermore, that by means of the benchwalls herein described and the asbestus covering for the steam-coils I am enabled to greatly increase their durability.

Having thus describedmyinventimnwhatI In testimony that I claim the foregoing I claim, and desire to secure by Letters Patent, have hereunto set my hand and seal.

1s X 3 w In a steam-boiler furnace, the combination ISAAC MLRRLLL' 5 0f the grate-bars D D, cast-iron plates E E, Witnesses:

bench-walls F F and perforated steam-coil G, 'WILMER BRADFORD, substantially as shown and described. CHAS. E. KELLR 

